1. Technical Field
The present invention relates generally to fiber optic network devices, and more particularly to fiber optic network devices configured based on a port mapping scheme arranged in distributed network architectures having multi-levels.
2. Technical Background
Optical fiber is increasingly being used for a variety of broadband applications including voice, video and data transmissions. As a result of the ever-increasing demand for broadband communications, telecommunication and cable media service providers and/or operators are expanding their fiber optic networks to increase their networks' capacity and reach to provide more services, applications and information to more proximate and distant subscribers. To facilitate this capacity and reach, the fiber optic networks must employ additional fiber optic cable, hardware and components resulting in increased installation time, cost and maintenance. This results in the fiber optic networks becoming more complex, requiring architectures that allow for the most efficient delivery of fiber optic service to the subscriber. These architectures typically employ fiber optic network devices, such as optical connection terminals, for example, in branches of the fiber optic network. The fiber optic network devices act to optically interconnect the fiber optic cables of the branch, separate or combine optical fibers in multi-fiber cables, and/or split or couple optical signals, as may be necessary.
For example, a multi-fiber feeder cable from a central office or a transport cable from a head end, may connect to multiple multi-fiber distribution cables. Each distribution cable then may extend to a designated geographic area, thereby providing the optical service to subscribers in that area. A fiber optic drop cable from the subscriber premises may connect to the distribution cable to establish optical connectivity between the service provider and the subscriber in a fiber to the premises (FTTP) optical network. However, extending the drop cable from the subscriber premises all the way to the distribution cable may require a substantial length of drop cable resulting in extensive cost and installation time. Moreover, the cost and installation time would be increased and compounded if a separate connection to the distribution cable was needed for each drop cable. To reduce the attendant cost and timing, while still maintaining optical connectivity between the distribution cable and the drop cable, and, thereby, between the service provider and the subscriber, one or more intermediate optical connection points, between the distribution cable and the drop cable may be incorporated.
To incorporate the intermediate optical connection points, a branch of the fiber optic network off of the distribution cable is established. The branch may be established at a branching point on the distribution cable, such as at a mid-span access location. An optical connection terminal may be used as the intermediate optical connection point and be centrally located to all of the subscribers being served by that branch. Therefore, the drop cables may extend from the subscriber premises and connect to ports on the optical connection terminal instead of directly to the distribution cable. However, the optical connection terminals typically are configured for and adapted to optically interconnect to the distribution cable only the drop cables connected to that particular optical connection terminal. Thus, each optical connection terminal has its own dedicated branch, i.e., stub cable, to provide optically connectivity with the distribution cable at the mid-span access location.
In situations where there are many subscriber premises to be served by one mid-span access location, more than one optical connection terminal in the branch from that one mid-span access location may be needed. This is particularly applicable where the subscriber premises are separated by appreciable distances, for example without limitation, in rural areas. In such case, given the above-mentioned configuration of the optical connection terminals and due to the dedicated branch (stub) cable, a separate branch with associated branch cable may have to be extended from the mid-span access location to each optical connection terminal.
Similar to the drop cable situation, the cost of the branch cable is generally charged on a per foot installed basis. Accordingly, installing separate branch cables from one mid-span access location to each optical connection terminal may be excessively costly and time consuming. Alternatively, an additional enclosure may be used with individual optical connection terminals to separate out the optical fibers from the branch cable for extending to the optical connection terminal and connecting to the drop cables. Either such case is expensive and time consuming. As such, the current configuration of the optical connection terminal precludes the feasibility of designing and using effective distributive hierarchical branching architectures as the FTTP optical network extends toward the subscriber premises.